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inkslinger77 writes "The two Mars rovers that have been carefully conserving critical power supplies since June, when the summer dust-storm season began on the red planet, are now springing back to work as the storms subside.
Typically, the solar panels on each rover produce about 700 watt-hours of electricity per day — enough to light a 100-watt bulb for seven hours, according to NASA. But this year's dust storms reduced that to as little as 128 watt hours per day. When daily power generation is down to less than 400 watt-hours, the rovers suspend their driving on the planet and stop using their robotic arms, cameras and other instruments.
But they are back in action now!"

Looks like IDG (ComputerWorld) is really hitting Slashdot HARD, either that or they have a deal with Slashdot. Here's a partial list of the shills that regularly show up and have almost 100% article acceptance rates:

inkslinger77

narramissic

jcatcw

If it's all OK and everything with the corporate ownership of Slashdot to be played by IDG, I suppose that's their business, but one would hope that they are actually getting PAID for being part of IDG's advertising program. And of course there should be disclosure so that visitors to Slashdot realize they are reading advertisements and not an article submitted by a "real" user...

each rover produce about 700 watt-hours of electricity per day -- enough to light a 100-watt bulb for seven hours, according to NASA.

I don't think you need NASA to say that - I think I can confirm that 700 watt-hours will power a 100-watt bulb (or device) for 7 hours. furthermore, improving on NASA, I can also say that it will power 7 100-watt bulbs for 1 hour, or 1 700-watt bulb for an hour.

Yep, I think it would be better judged as a percentage. Though I have noticed that some of them new fangled >1000000 users have been coming up with some pretty funny posts recently. Positively shocking.

indeed;) I maybe would have been in the 7 or 8 hundred thousands if I'd registered when I started reading.. meh. I became a bit of a watered down geek when I started studying Computer Science, because it meant I was spending less time with computers/coding..:(

Going one further than NASA, I can also reveal that the rover only ended up getting power equivalent to lighting one 100-watt bulb for 1.28 hours, or 128 1-watt bulbs for an hour, or one 1-watt bulb for 128 hours.

Since a watt is just a short way of saying one joule per second, this means

700 joules per second per hour per day

Do NASA really do their energy computations in this unit? Given their past problems getting to grips with the metric system, perhaps they might.

Surely it would be clearer to say 'the rover's solar panels have an average power output of about 29 watts'. Anyone could see that this is enough power to run a 100 watt lightbulb nearly one-third of the time.

Yes - I realized my mistake as soon as I wrote the comment and posted a correction, but Slashdot disallowed it for coming less than 2 minutes after the previous comment. I didn't read that and closed the window. You are absolutely right, it should be 700 joule-hours per second per day.

Surely it would be clearer to say 'the rover's solar panels have an average power output of about 29 watts'.

Yeah, but how many watt-hours per hour?;-)

(Btw, as others pointed out, I think you meant 700 "joule-hours per second-day" or "joules per second per (day per hour)" or "(joules per second)-(hours per days)es". Recurring isometric units are fun!)

Putting things in useful units is important. But a the same time, some people have bizarre views on what consitutes useful. For example, in fractions relat

There is no such thing as 79% of a dollar... what are you gonna do, cut one up? That is illegal. However, you can have 79 cents, which just happens to also have a value that is 79% of the value of a dollar.

Besides, the image of California getting a big pile of pennies and assorted change every time someone sends a dollar to the Feds just seems sort of warm and happy. Ahh, change. Can ya spare some?

I initially had the same objection as you, but then I realized that the "watt-hours per day" unit actually makes sense.The rovers' solar panels only generate power during daylight, and even then the generated power varies continuously as the sun angle changes. So talking about average power production produces a misleading picture of how the power is actually delivered; in many ways, it's more useful to think about some number of watt hours being accumulated per day as a lump sum, with nights separating th

Of course, none of those statements are true as if the solar panels produce 700 watt-hours in a single (martian day) they average only around 57 watts over the course of the sunlight hours, with a peak of 114 watts, putting output above 100 watts for 5.47 (earth) hours. So you can run a 100 watt light bulb for only 5.47 hours.

Fortunately they are not into consumer electronics.
Otherwise there'd be a DRM [wikipedia.org] on these rovers, one they would have retired 3 years ago in a cruel, wanton act of planned obsolescence [theinquirer.net].

Are you kidding? These rovers are functioning way beyond their mission parameters. They've collected more data than anyone expected. We've gone from "What if there's water on Mars" to "How much water is there on Mars?". The rovers survived a Martian dust storm! Martian dust storms have been known to cover the entire planet.

Let's put it this way. If your car was as well-designed and resilient as these rovers it would run on empty for 100 miles, drive up mountains, and review your tax returns.

I think it's more like providing parameters for a car such as: "well, it might get 3 miles to the gallon, have a range of 30 miles, not function at all on rainy dais, and explode on contact with anything larger than a bowling ball", but then delivering a regular car.

In the space business, if you have hardware on mars, it's already magnitudes better than anything newly developed that hasn't launched yet. Abandoning an old project for a new one risks the new one not making it there successfully. Far better to use what you have as long as you can. It it ain't broke....

This is a concern, but NASA considers the work the rovers are doing valuable enough to keep funding it.

NASA's budget for 2007 provides $85 million for rover operations, communications, and data processing. Obviously that's a non-trivial amount (roughly enough to employ 350 people full-time, standard cost ratios), even compared to the $820 million spent on designing, building, launching, and operating for the first year.

For comparision, Hubble is receiving $340 million this year. The entire NASA budget for Mars exploration for 2007 is about $700 million. Almost half of that goes towards building the 2009 Mars Science Laboratory rover. The rest is divided between the Spirit and Opportunity, Mars Global Surveyor (which died a couple months ago), Mars Odyssey (orbiter), Mars Reconnaissance Orbiter, the US contributions to Mars Express (orbiter), Phoenix Polar Lander (lander, en route), and a Scout-class mission scheduled for 2011.

* My numbers came from NASA's 2007 budget request. Some of them were changed for the actual allocation.

It makes me wonder about the properties of the dust and storm. The first time the Rover's panels got cleaned, everyone seemed suprised. What is it that is making a dust storm that is expected to cake on the Rovers, instead clean them? Air speed? Particle size? Luck?

The rovers normally do a sun stare (through thick h-a filters I believe) to measure tau, the fraction of sunlight that's making it through the atmosphere. Here's a mosaic of those sun stares [planetary.org] from the last month or so, corrected to show the light as it would actually appear to the rover. The dramatic darkening of the sun is obvious. The feat of building rovers that not only live (at time of writing) thirteen times over their design lifetime, but survive on less than half the power that was originally expected to kill them both stone-dead, is going to be a legend in unmanned spaceflight for a long time to come... (For the last 3 years, those of us following the rovers on a daily basis believed the official line that less than 280Wh/day would mean bricked rover after a couple of days. The minimum Oppy received was 128 W/h - and (thanks partly for the nice warm summer weather) it didn't even trip the emergency heaters which come on at 39*C below.
Kudos to Emily Lakdawala of the Planetary Society, who got an awesome congrats note from Jim Bell, the MER imaging lead [postcardsf...rsbook.com].

The untold story of the MER rovers is the triumphant vindication of Steve Squyres' then unprecedented decision to allow the raw imagery to be automatically thrown up on the net virtually as they came in - so that in some cases, the amateur mosaics, panoramas and other post-processed images were sometimes out before the official JPL team had even seen the raw data. Indeed someone even wrote an application [blogspot.com] specifically to pull down, process and render the raw data. (Yeah, it's GPL'd:) )

The issue of whether or not to put some sort of dust-clearing device on the panels was examined critically and decided on early in this project. In short: they didn't know what dust storms would do to the panels; it turns out they tend to remove dust. Several options for dust clearing were considered -- wipers, electrostatic techniques, peel-away plastic, and probably others I've forgotten. All of them would have *probably* worked, and all of them would have taken up space and weight. Essentially it came down to choosing between dust removal and an instrument. Faced with that decision, they decided that better quality, more complete data was more interesting than having the rovers run longer.

Of course, they got lucky, and the dust storms seem to clear dust off the panels. So there was even less need for dust-clearing than they thought there might be.

I thought they knew what dust storms would do, they've had rovers and landers on Mars before, that experience helped temper their expectations on how long it could last. What helped was that they rolled over a ridge and managed to catch enough of the Martian wind to clear the panels.

...because surely, they'd be annoyed with anybody choosing "three years or more" for million-to-one odds on the bet as to how long these rovers would last...

...and they just keep on going! I am fucking amazed at how overdesigned these thing are; broken wheels, mini tornadoes, planet-wide dust storms; nothing (so far) seems to be able to keep these machines down, and in some cases, theoretically adverse conditions are helping them to keep going!

I think it's amazing that these rovers still keep going. Not that I doubt in engineering skills of people involved, but they "just keep on working", which I find pretty extraordinary. You'd think that any equipment left in such harsh conditions would turn into trash very soon. I was almost sure that at least one of them wouldn't survive the storms, but, fortunately, reality proved me wrong. Go NASA!

I was almost sure that at least one of them wouldn't survive the storms, but, fortunately, reality proved me wrong. Go NASA!

I actually think it's kinda surreal, the way they just keep going.
If mankind ever makes it to Mars in the flesh, I hope they bring one back and give it a medal or something.
Maybe mount a plaque at the point where it 'died' on Mars as well.

I actually think that the engineers who designed it had a pretty realistic view of how much punishment the rovers could handle, but if you get the same amount of money whether you say "We are sure it will work for X time" or "We are sure it will work for 5X time", why not go for the first? If something horrendous happens after 2X time, your ass is pretty much covered, and everyone will just say 'Wow! It had an operation time of twice the expected!" instead of "We're never gonna hire those yolks again, their

I grew up in a coal mining area of Illinois. The worlds largest shovel (Marion 6360 [stripmine.org]) was in the mine where my dad worked...and it used the same crawlers that NASA made for the space shuttle. Down at NASA, they have the thing crawl out on a carefully leveled bed of pea gravel....but down in the mines, they had some mats to lay down, but the crawlers would still crunch over stuff. Apparently, when some of the NASA people came up to look at how the shovel was doing on their crawler system, they were utterly

Why are you describing to slashdotters, 700 watt-hours will light up a 100watt bulb for 7 hours? Is it that easily imaginable? Should use very precise engineering descriptions like, four football fields long or as big as a refrigerator or something. The most descriptive way to describe 700 watt-hours would be something like the energy spent by a senator tapping the restroom stall floor with foot over his entire three term career or the energy used by a/. mod marking 8324 posts as trolls, flamebaits and underrated.

700 watt hours. That's enough to run your Gaming PC for 6.5 minutes, or light 42,338 super bright white LED's at 125% brightness for 1 second in a blindingly bright flash that will make everyone for miles say "WOW! THAT WAS BRIGHT!"

We as software developers here should take note of this. The code you're writing and putting into production has the potential to last for decades. For example, out of college my first programming job was for Mutual of Omaha. They had lots of code that was written in the late 1960s in Assembler or in (gag) COBOL. Well, although someone like me would have loved to have rewritten those systems, it was not happening. Then, take another point. I myself wrote a large system for them that--according to friends who are still there--and that system has not been changed much since then.
So, folks, the point is this: you write a lot of applications. Some won't survive a year. Others... they may be doing their job in twenty years. Machines wear out but--properly designed and maintained--software never does.
Bravo to Spirit & Opportunity and the teams that built those kickass pieces of hardware/software.

I think a lot of us learned this lesson in the midst of the Y2K hoo-hah. And I don't see the need to gag at COBOL, it played a huge part in getting computers into daily life. Sure, it has some flaws, and anybody who ever used an ALTER statement should be shot on sight, but any language can be misused.

And I don't see the need to gag at COBOL, it played a huge part in getting computers into daily life.

And war played a huge part in medical advancements, used daily in our lives. That doesn't mean war is good. Come on...there are reasons you don't see people scrambling to do new coding and project development in COBOL.

Not to rain on your parade, but I just fixed some veterinary office software for a local animal hospital that was written in COBOL. Yes, it was on a PC and I thank the Gods it was interpreted and thus included the source code. It had been 20 years since I've worked with COBOL.

I was fixing it because the original programmer -- and I am NOT making this up -- committed suicide. Hmmmm...I wonder if there is a connection?

"I thank the Gods it was interpreted and thus included the source code. "Huhhh? interpreted Cobol? I haven't seen a Cobol interpreter since I worked on a SuperPet back in the dark ages?BTW the SuperPet was a great system for schools. I had Pascal, Fortran, Cobol, APL, Basic, and an Assembler. What was best of all the where all interpreters with the possible exception of the Assembler.

Actually, the rover software has been updated several times since launch, most recently four or five months ago. They've added new features like "go and touch" (a development of the previous "touch and go".) TnG means they park by a rock, make sure it's in range of the arm, then they can uplink a sequence saying "get the arm out, study the rock with the Mossbauer / micro-imager / RAT / etc, then put it away and drive 35 metres on heading 182 degrees". It used to take a day or so of fine adjustments after t

I wondered whether a radioisotope thermoelectric generator (RTG) would have been a good choice. The batteries used weigh 7.15 kg to deliver about 100 W (1 [space.com]). RTGs in development to deliver about the same power weigh 34 kg and 2). These RTGs are being developed for the next generation rover, the Mars Science Laboratory.

Sigh. It's practically obligatory when you're talking about science (at least in the States, how about other countries?) to dumb it down. At least they didn't say how many ping-pong balls the rovers could carry if they were hollow.

And at least we aren't to the point of saying how many angels can dance on a rover's solar panel, or somesuch. Yet.

You could also run 35 4 Watt bulbs for 5 hours.Nothing special in making up these type of calculations. For all-integer solutions, all you need to do is get the factors of the base number (700 Watts), which in this case are "2, 2, 5, 5, 7", then put these numbers in an equation of the form "A (count) B (wattage) Bulbs for C (time) hours". Replace A, B, and C with permutations of the factors multiplied together.

If you don't understand that, then just randomly choose A and B, and calculate C using "C = 700 /